This invention relates to a method of preparing albumin rich foodstuff raw material consisting essentially of soya beans and not containing salt.
Like meat, as a source of albumin, soya beans are important foodstuffs as a source of supplying albumin to human bodies. "Miso", one of the products of soya beans is an important foodstuff for Japanese. However, due to recent change in social life, especially due to decrease in hard labor, the quantity of salt required by human bodies is now decreasing. Too much salt affects the health (causing high blood pressure, kidney disease, etc.) so that it is necessary to limit the quantity of salt taken into human bodies. For this reason, attempts have been made, to develop foodstuffs containing little or no salt.
In a paper of H. Iwashita et al an Miso Technique No. 86 issued on Apr. 16, 1961 their is disclosed a method in which a mixture of boiled or steamed soya beans and a rice malt is maintained at a temperature of from 45.degree. to 55.degree. C. for 24-36 hours, then 3-5% by weight of 95% ethyl alcohol is incorporated at a temperature of about 40.degree. C. Thereafter, the mixture is left to stand at room temperature for about one week to improve the flavor and taste and to age the mixture. When miso is prepared according to this method, acidification caused by usual live fungus, for example, lactic acid bacilli and aerotropic decomposing bacteria can be prevented by temperature control. However such a control device is bulky and expensive. Furthermore, according to this method, the mixture of the boiled or steamed soya beans and the rice malt is semi-solid, and moreover since the quantity of ethyl alcohol incorporated is extremely small, not only the mixing step is difficult to perform but also it is almost impossible to obtain a homogeneous mixture.
Japanese laid open patent specification No. 48498 of 1976 discloses a method of preparing soya bean miso in which all or a portion of the salt incorporated into a mixture of steamed or boiled soya beans is substituted by less than 100% by volume or preferably less than 5% by volume of alcohol for the purpose of preparing soya bean miso not containing or containing but a small quantity of salt. Although this method is more advantageous than the first mentioned method in that there is no difficulty to temperature control and incorporation of alcohol, where rice malt or wheat malt is used, substitution of alcohol of less than 5% by volume makes it difficult to suppress the adverse effect of the lactic acid bacilli or the like thus resulting in acidification. Consequently it is difficult to determine optimum aging interval. Even when the quantity of alcohol is increased beyond 5% by volume it is impossible to sufficiently suppress the adverse effect of the lactic acid bacilli, etc. When the quantity of alcohol approaches 10% by volume, the flavor of alcohol becomes remarkable thus degrading the quality of the product.